The beaver is an extinct giant rodent Castoridae family. It is one of the largest rodents that ever existed, which reached the size of a bear. He lived about 50,000 years ago during the Pleistocene in North America.He used his teeth to chew tough vegetation and bark, was a good swimmer, but did not build dams. Other types of beaver build dams to protect themselves from predators but in this case was protecting its own gigantic size, were found fossils of giant Castor from Florida (southern U.S.) to northern Canada.Unlike the current beaver had a wider rear legs relative to its body, making it easier to swim faster.Other differences are observed in the teeth. The cutting teeth (incisors) of the giant beaver were up to 15 cm long.Despite their general similarities, the giant beaver and the modern beaver are not close relatives. The giant beaver Castoroides is classified in the genus, while the modern beaver Castor belongs to. There are two species of beaver giant Castoroides Castoroides ohioensis and leiseyorum.